The present invention concerns a method and a device for compressing and decompressing light field images and more particularly a plenoptic image from a light field camera capture and a refocused image computed from it.
A light field camera, also called a plenoptic camera, is a camera that uses a microlens array to capture four dimensional light field information about a scene. Light field cameras may also be composed of multiple traditional cameras instead of using a microlens array.
A light field camera system provides a set of sub-images. These images are usually integrated into a single image. This single image is called the light field image or the plenoptic image. As this single image is composed of highly correlated sub-images, the single image can be compressed in an efficient way. For example, the images from the plenoptic camera may be compressed by using vector quantization. Other compression algorithms could be used. The single image composed of the multiple sub-images will be called the plenoptic image herein.
The main advantage of such light field cameras is that it is possible to compute from the plenoptic image an image in which the focus can be arbitrarily chosen. After shooting, the photographer can choose the focus, try several, and obtain images of the same scene with different focus. An image obtained for a given focus from a plenoptic image will be called a refocused image herein.
Typically, at the time of shooting, a plenoptic image is obtained. Based on this plenoptic image, the photographer can obtain a refocused image by post-processing. This refocused image can be obtained directly on the camera (for example, the photographer chooses directly an area of interest on the screen of the camera for triggering the refocusing algorithm) or on a personal computer when the plenoptic picture is loaded. This refocused image corresponds to the choice of the photographer for the generation of the refocused image. Therefore, it is desirable to consider the set of images constituting the plenoptic image as the result of the shoot and the refocused image as the result of the post-processing process. It would be advantageous to obtain an efficient method to compress both the plenoptic image and the refocused image.